Sleeping Away Winter: The American Black Bear

Spring is on its way and that means winter hibernations are ending. One hibernating Virginia mammal we see on camera traps is the American Black Bear (Ursus americanus). They entered their dens around November and now that it’s spring, they are emerging. Black bears have a wide range across North America which is shown in the map below. In the more Northern latitudes they can hibernate for up to 7 months. Here in Virginia though, it’s usually shorter and they may even emerge from their dens to forage during the winter if the weather is warm enough. If there is abundant food available during the winter in more Southern areas, black bears may not even hibernate at all.

American black bear range

Range map of American Black Bears from Encyclopedia of Life

In preparation for their winter hibernation, black bears will put on a large amount of fat. Black bears are opportunistic omnivores so while they do eat meat, a majority of their diet is what’s available such as fruits, nuts, and insects. Since they are so opportunistic, they will eat any food humans leave out such as garbage.

Black bear carrying a bag of garbage

 In this region, a key way they increase their fat reserve is from eating the fall mast. Mast is the dry fruit from woody plants such as nuts from oak, hickory and beech trees. The mast production is a critical food source for many forest species in the fall and winter. Black bears will enter their den once they’ve built up a sufficient reserve. Some of the most common dens are hollow trees, rock crevices, under root masses, or even brush piles.

Many hibernating mammals will experience a drastic decrease in their body temperature while hibernating. However, a black bear’s body temperature doesn’t drop a significant amount. This allows them to stay somewhat alert and respond to danger much quicker. Their heart rate though, will drop from around 30-50 beats per minute to 8 beats per minute. Female black bears give birth around January and February while they are hibernating. Usually females give birth to a litter of 2 or 3 cubs but their litter can be as big as 6 cubs!

Three black bear cubs

The cubs will nurse for the rest of the hibernation while the mother continues to fast. Then these cubs will stay with her for nearly two years. Only after a second winter hibernation with her will they emerge in the spring and leave her to establish their own territory. Now that it’s the beginning of April, you’re likely to start seeing black bears in your camera trap images. You may even see a mother and her cubs.

Camera trap image of mother black bear with two cubs

Since you may see bears when hiking or deploying camera traps, here are some tips to keep you and the bears safe!

  • Maintain a safe distance from the bear. This is especially important if you see a mother bear with cubs.
  • Make noise so that the bear is aware of you.
  • Never try to feed a bear. This will teach them to associate humans with food.
  • Do NOT run from a bear. You may slowly back away but running will signal the bear to pursue you.

For more bear safety, please visit the following National Park Service webpage:


IUCN (International Union for Conservation of Nature) 2016. Ursus americanus. The IUCN Red List of Threatened Species. Version 2017-3.

Kronk, C. 2007. "Ursus americanus", Animal Diversity Web. Accessed 29 March, 2018 available from Encyclopedia of Life.

"Ursus americanus: American Black Bear", Smithsonian’s North American Mammals. Accessed 29 March, 2018 available from Encyclopedia of Life.